 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.runtime.auth;

 import java.net.MalformedURLException ;
 import java.net.URL ;
 import org.eclipse.core.runtime.Assert;

 /**
  * A utility for manipulating <code>URL</code>s.
  */
 public class URLTool {

     /**
      * Returns the parent URL of the given URL, or <code>null</code> if the
      * given URL is the root.
      * <table>
      * <caption>Example</caption>
      * <tr>
      * <th>Given URL</th>
      * <th>Parent URL</th>
      * <tr>
      * <td>"http://hostname/"</td>
      * <td>null</td>
      * <tr>
      * <td>"http://hostname/folder/file</td>
      * <td>"http://hostname/folder/</td>
      * </table>
      *
      * @param url a URL
      * @return the parent of the given URL
      */
     public static URL getParent(URL url) {
         String file = url.getFile();
         int len = file.length();
         if (len == 0 || len == 1 && file.charAt(0) == '/')
             return null;
         int lastSlashIndex = -1;
         for (int i = len - 2; lastSlashIndex == -1 && i >= 0; --i) {
             if (file.charAt(i) == '/')
                 lastSlashIndex = i;
         }
         if (lastSlashIndex == -1)
             file = ""; //$NON-NLS-1$
 else
             file = file.substring(0, lastSlashIndex + 1);

         try {
             url = new URL (url.getProtocol(), url.getHost(), url.getPort(), file);
         } catch (MalformedURLException e) {
             Assert.isTrue(false, e.getMessage());
         }
         return url;
     }
 }

